Source : WordNet®

one-on-one
     adj 1: directly between two individuals; "one-on-one instruction"
     2: being a system of play in which an individual defensive
        player guards an individual offensive player; "one-on-one
        defense" [syn: {man-to-man}]
     adv : (of two persons) in direct encounter; "preferred to settle
           the matter one-on-one"; "interviewed her
           person-to-person" [syn: {person-to-person}]